Examples relate to cementing operations and, in certain examples, to set-delayed cement compositions and methods of using set-delayed cement compositions in surface operations.
Cement compositions may be used in a variety of surface operations. For example, in roadway repair, a cement handling system may pump cement into a pothole or other such fissure in a road. Similarly, cement may be used to repair other surface structures such as patios, sidewalks, fountains, etc. In waste solidification applications, cement may be added to waste to bind and solidify the waste, making it less dangerous and easier to handle. In soil stabilization applications, cement may be mixed with soil to stabilize the soil, which may increase its strength and bearing capacity. In a similar manner, cement may also be used to stabilize the foundation of a structure.
A broad variety of cement compositions have been used in surface cementing operations. In some instances, set-delayed cement compositions have been used. Set-delayed cement compositions are characterized by being capable of remaining in a pumpable fluid state for at least about one day (e.g., at least about 7 days, about 2 weeks, about 2 years or more) at room temperature (e.g., about 80° F.). When desired for use, the set-delayed cement compositions should be capable of being activated whereby reasonable compressive strengths are developed. For example, a cement set activator may be added to a set-delayed cement composition whereby the composition sets into a hardened mass. Among other things, the set-delayed cement composition may be suitable for use in surface applications, for example, where it is desired to prepare the cement composition in advance. This may allow, for example, the cement composition to be stored prior to its use. In addition, this may allow, for example, the cement composition to be prepared at a convenient location and then transported to the job site. Accordingly, capital expenditures may be reduced due to a reduction in the need for on-site bulk storage and mixing equipment. This may be particularly useful for applications where space and equipment may be limited.
While set-delayed cement compositions have been developed heretofore, challenges exist with their successful use in surface cementing operations. For example, set-delayed cement compositions prepared with Portland cement may have undesired gelation issues which can limit their use and effectiveness in cementing operations. Other set-delayed compositions that have been developed, for example, those comprising hydrated lime and quartz, may be effective in some operations but may have limited use at lower temperatures as they may not develop sufficient compressive strength when used in applications where low temperature may be an issue.